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Porsche M96 and M97 (bóxer de seis cilindros atmosférico, 2,5 a 3,8 litros)Urgency: As soon as possible

Deep metallic engine knock in the Porsche M96/M97 engine: causes

In the Porsche M96/M97 engine, 2 documented faults may be the cause: failure of the intermediate shaft bearing (IMS) on the M96/M97 and scored cylinders (bore scoring) and ‘Kolbenkipper’ on the M96/M97.[1][5][6]

What to do now

As soon as possible

Switch the engine off and do not drive on. Carrying on can snap a connecting rod and leave the engine beyond repair.

What it means

A deep knock that gets louder with engine speed usually points to internal damage, such as big-end bearings worn through lack of lubrication. It is one of the most serious faults an engine can have.

Engine knock: causes in all cars

13 sourcesHow we work

Engine faults that cause it

From most to least important. Under each fault, how the symptom shows up. Check the affected years and versions on each page.

  1. Source for the symptom[1]

  2. Source for the symptom[5][6]

Other common causes: engine knock

Besides the documented faults of the Porsche M96/M97, these are the most common causes on any car according to the sources.

  • Play in the big-end or main bearings (rod knock)[10][11]Common
  • Lack of lubrication: low or degraded oil or insufficient pressure[11][12]Common
  • Stretched timing chain or tensioner without pressure[10][11][13]Possible
  • Hydraulic tappets and valves with play[10][11]Possible
  • Worn pistons and rings[11]Uncommon
  • Normal diesel engine noise[11]Possible

What to check first

  1. Stop the engine as soon as it is safe and check the oil level with the dipstick on level ground and with the engine cold or stopped for a few minutes; it is the first step recommended by Todoaditivos and RACE.[10][12]
  2. Look at the oil pressure warning light (red): if it is on along with the knocking, don't start the engine again and call assistance.[10][12]
  3. Note when it makes the noise: only when cold and for a few seconds (probably tappets or tensioner), or with the engine warm and growing with load and revs (much more serious).[10][11]
  4. Look for oil leaks on the ground or blue smoke, signs that the engine is losing or burning oil, according to RACE.[12]
Complete guide: deep metallic engine knock

Cars with the Porsche M96/M97 engine

Open yours to see only the faults that affect it according to its years and versions.

Frequently asked questions

Engine knock in the Porsche M96/M97: what could it be?

In the Porsche M96/M97 engine, 2 documented faults may be the cause: failure of the intermediate shaft bearing (IMS) on the M96/M97 and scored cylinders (bore scoring) and ‘Kolbenkipper’ on the M96/M97. Each fault has its own page with the affected years and versions, the cause and how to check for it.

Engine knock in the Porsche M96/M97: is it serious?

Urgency: as soon as possible. Switch the engine off and do not drive on. Carrying on can snap a connecting rod and leave the engine beyond repair. The most serious fault that causes it on this engine has critical severity.

Sources

Every fact on this page links to its source. If you find an error, let us know.

  1. 996 Buyer's GuideRennsportKC · Other source · published 10 March 2011 · consulted 2 November 2026
  2. 1st Generation Porsche Boxster 986 Buyer's GuideStuttcars.com · Motoring press · consulted 2 November 2026
  3. Porsche 996: Complete Buyer's Guide to the Water-Cooled 911 (1997 to 2006)Renn Driver · Buying guide or workshop · published 30 October 2026 · consulted 2 November 2026
  4. Porsche Cayman and Boxster Common Problems: A Specialist Field GuideForeign Automotive · Buying guide or workshop · consulted 2 November 2026
  5. Porsche 996 (1997-2006) Kaufberatung: Stärken & Schwächenauto motor und sport · Motoring press · published 11 December 2018 · consulted 2 November 2026 · in German
  6. What are the most common 996 Issues?Flat Six Innovations · Buying guide or workshop · published 23 November 2025 · consulted 2 November 2026
  7. Porsche 911: 5 Generationen im Gebrauchtwagen-CheckAUTO BILD · Motoring press · published 22 September 2026 · consulted 2 November 2026 · in German
  8. The Definitive Guide To Porsche 997 Engines (M96.05, M97, MA1)FCP Euro · Other source · published 16 January 2024 · consulted 2 November 2026
  9. Porsche 911 Common Problems: Every Generation, Every Major IssueRenn Driver · Buying guide or workshop · published 4 May 2026 · consulted 2 November 2026
  10. El motor hace ruido en frío: qué es cada ruido y cuál preocupaTodoaditivos · Other source · consulted 29 October 2026 · in Spanish
  11. ¿El motor diésel de tu coche emite un ruido y un traqueteo?RACE · Motoring press · published 22 June 2023 · consulted 29 October 2026 · in Spanish
  12. ¿Qué pasa si el coche se queda sin aceite?RACE · Motoring press · published 26 August 2020 · consulted 29 October 2026 · in Spanish
  13. Las graves (y costosas) averías que puede causar en tu coche la rotura de la cadena de distribuciónDiariomotor · Motoring press · published 17 July 2020 · consulted 29 October 2026 · in Spanish